Roller bearing

ABSTRACT

The anti-seizure property of the contact sections between the inside surfaces  11   a   , 11   a  of the outward-facing and inward facing flange sections  8   a   , 10   a , and the axial end surfaces of the rollers  5   a  is improved, and the axial load capacity at the sections is improved.  
     A roller bearing is provided to have rollers  5   a  which have axially opposite ends in contact with the inner side surfaces  11   a   , 11   a  of an outward-facing and inward-facing flange sections  8   a   , 10   a  and in a tapered convex surface  22, 22  such that the outer diameter of the tapered convex surface  22, 22  becomes larger toward the middle of the rollers  5   a , and that the line normal to the generatrix at the centers S, S of the convex surface  22, 22  passes through the center O of the rollers  5   a . As a reluts, no moment to make the roller  5   a  tilt occurs with the force applied to the contact sections between the tapered convex surface of the rollers  5   a  and the inside surfaces  11   a   , 11   a  of the flange sections  8   a   , 10   a.

TECHNICAL FIELD OF THE INVENTION

The roller bearing of this invention is used for supporting a rotatingshaft, such as a rotating shaft used in industrial equipment such as arolling mill, or the rotating shaft of a gear transmission used inrailroad cars, construction equipment or the like, to which not onlyradial loads but also axial loads are applied during operation; suchthat it supports the rotating shaft so as to rotate freely with respectto a stationary section such as a housing. More particularly, thisinvention relates to a roller bearing that is capable of sufficientlymaintaining its seizure resistance even when heavy loads, vibration,impact, fluctuating loads and the like are applied during rotating athigh speed.

BACKGROUND TECHNOLOGY OF THE INVENTION

Axial loads, in addition to radial loads, are applied to the supportshaft that is fastened to the end of the roll of a rolling mill, or tothe rotating shaft that is fastened to the helical gear of a geartransmission for driving a railroad car. Therefore, the rolling bearingfor supporting these rotating shafts such that they can rotate freelywith respect to the housing must be able to support radial loads as wellas axial loads. In order to accomplish that, conventionally it has beencommon to support the rotating shaft with respect to the housing usingat least one pair of tapered roller bearings that have different contactangles, or using an angular ball bearing, deep-groove ball bearing, or3-point or 4-point contact ball bearing, or using a cylindrical rollerbearing together with the bearing as mentioned above.

However, in the case of supporting the rotating shaft with an angularball bearing, deep-groove ball bearing, or 3-point or 4-point contactball bearing, the radial load that can be supported is less than theradial load that can be supported with tapered roller bearings.Therefore, in order to support large radial loads, it is necessary tocombine these bearings with a cylindrical roller bearing as mentionedabove. However this results in an unavoidable increase in the dimensionsof the rotation-support section. On the other hand, in the case ofsupporting the rotating shaft with the tapered roller bearings,adjusting the clearance in the tapered roller bearing is verytroublesome. Particularly, the temperature of the housing sectiongreatly changes due to seasonal changes and furthermore due to theeffects of heat generated by surrounding equipment. In order to preventthe tapered rollers from seizing up or causing backlash regardless ofthere being this kind of large temperature change, the internalclearance of the tapered roller bearings must be very preciselyadjusted, which is troublesome.

Moreover, in addition to the fact that the radial load that can besupported by these tapered roller bearings is less than the radial loadthat can be supported by a cylindrical roller bearing, it is alsoimpossible to avoid large slippage that occurs at the area of contactbetween the surface on the large-diameter end of the tapered roller andthe surface of the flange section that fits around this surface. Largeslippage at this area of contact increases the friction on each surfaceand makes it easier for damage such as slippage marks or smearing, or inextreme cases, damage due to scraping or seizure to occur. Also, thewear on each surface due to this slippage increases the internalclearance, so in the case of tapered roller bearings used in the drivemechanism for a railroad car for example, it is necessary toperiodically adjust this clearance, and this adjustment of the internalclearance also is troublesome. On the other hand, in the case of anN-type or NU-type cylindrical roller bearing, the radial load that theycan support is greater than the radial load that can be supported by thetapered roller bearings, however, it is not possible to support loads inthe axial direction only with the cylindrical roller bearing.

Therefore, this kind of cylindrical bearing must be used together withthe tapered roller bearings or ball bearings, and thus it is impossibleto avoid an increase in the dimensions of the rotation-support section.

Conventionally, in order to solve these problems, the use of acylindrical roller bearing having a race with a flange section, as shownin FIG. 13, as the rolling bearing for supporting the rotating shaft inthe housing, was proposed. For example, it is conventionally known inthe art as in Patent Literatures 1 to 3, and non-patent Literatures 1and 2. In the case of a N-type or NU-type cylindrical roller bearingdescribed above, it is not possible to support axial loads, even thoughradial loads can be supported, however, the roller bearing 1 shown inFIG. 13 is able to support axial loads because of the engagement betweenthe end surfaces in the axial direction of the rolling elements orcylindrical rollers 5, and the inner surfaces 11, 11 of the flangesections 8, 10 formed around the circumference of the inner race 2 andouter race 3, respectively.

In other words, this roller bearing 1 comprises an inner race 2, outerrace 3, flanged ring 4, a plurality of cylindrical rollers 5 and a cage6. Of these, the inner race 2 has a cylindrical-shaped inner-ringraceway 7 formed around the middle of its outer peripheral surface, andoutward facing flange sections 8, 8 formed on the opposite endsthererof. Also, the outer race 3 has a cylindrical shaped outer-ringraceway 9 formed around its inner peripheral surface except for one endin the axial direction (right end in FIG. 13) thereof, and there is aninward facing flange section 10 on the one end. In addition, the flangedring 4 is located such that it comes in contact with the other end inthe axial direction (left end in FIG. 13) of the outer race 3, and hasan inner-diameter section that protrudes further inward in the radialdirection than the outer-ring raceway 9 to function as the inward facingflange section 10. Moreover, the cylindrical rollers 5 are rotatablyheld in the cage 6 between the inner-ring raceway 7 and outer-ringraceway 9.

With this roller bearing 1, constructed as described above, the endsurfaces on the axially opposite sides of the cylindrical rollers 5 facethe pair of outward facing flange sections 8, 8 on the radially innerside and the pair of inward facing flange sections 10, 10 on theradially outer side, and thus the roller bearing supports axial loads inthe opposite directions by cooperation between the cylindrical rollers 5and the flange sections 8, 10. In other words, by supporting therotating shaft with the roller bearing 1 constructed as described above,such that it rotates freely with respect to the housing, it is possibleby the housing via the roller bearing 1 to support the axial loadsapplied to the rotating shaft. By using this kind of roller bearing 1,in addition to being able to support larger radial loads than thetapered roller bearings, the work of adjusting the internal clearanceduring assembly between the rotating shaft and housing is simplified.

The following are prior art technology with respect to the presentinvention:

Patent Literature 1: Tokukai Hei 8-93756

Patent Literature 2: Tokukai Hei 9-88970

Patent Literature 3: Tokukai 2001-151103

Non-patent Literature 1: “NSK Rolling Bearing Brochure” No. 140 c, 1995,page B81 published by NSK.

Non-patent Literature 2: “Rolling Bearing Brochure” No. 2202-II/J.1997.9. page B-92 published by NTN.

In the case of supporting axial loads with the roller bearing 1described above, the axial loads are only supported by the contact area(sliding contact area) between the opposite end surfaces of thecylindrical rollers 5 and either the outward facing flange sections 8 orinward facing flange sections 10. Therefore, at this area of contact,there is high-speed sliding contact when supporting large axial loads,and the PV value, which is the product of the contact pressure (P) andsliding velocity (V), becomes large. Especially in the case ofsupporting large axial loads, or in the case when the axial load is avibrating load or impact load, or when operating under severelubrication conditions (for example, minute amount of lubrication),there is a possibility of scraping or seizure occurring at the area ofcontact.

Moreover, when axial loads are applied to the roller bearing 1, a forceor so called “tilt moment” is applied to the cylindrical rollers 5 dueto the axial load that causes the axis of rotation of the cylindricalrollers 5 to tilt. In other words, when an axial load Fa is applied asshown in FIG. 13, the forces shown in the same figure by the arrows α, αare applied in opposite directions on the axially opposite ends of thecylindrical rollers 5 and on the radially opposite sides of cylindricalrollers 5. Also, these opposing forces become a moment force (tiltmoment), as shown by arrow β in FIG. 13, that is applied to thecylindrical rollers 5 to tilt the axis of rotation of the cylindricalrollers 5. Of course, when an axial load is applied in the oppositedirection of the axial load Fa shown in FIG. 13, a tilt moment in thedirection opposite the arrow β (counterclockwise direction) is appliedto the cylindrical rollers 5. This tilt moment tilts the cylindricalrollers 5, making it easy for the outer peripheral edge on the endsurfaces of the cylindrical rollers 5 to come in contact with the innersurfaces 11, 11 of the upward or outward facing flange sections 8, 10,or the inner-ring raceway 7 and outer-ring raceway 9. As a result, edgeloading occurs on the inner surfaces 11, 11 of these flange sections 8,10 and both of the raceways 7, 9, so that the durability of theseportions is reduced.

In the case of the structure with a cage, there are also problems asfollows; Specifically, the shape of the outer peripheral portion of theopposite ends in the axial direction of the respective cylindricalrollers 5 is relatively sharp-pointed (formed substantially at rightangles), and the shape of the pockets 12, 12 in the cage 6 for holdingthe respective cylindrical rollers 5 has an angular corner as shown inFIG. 14. Because of this, when the rolling contact surface of therespective cylindrical rollers come into contact with the inside surfaceof the respective pockets 12, 12, the stress applied to the cornerportion becomes easily large, and it may be difficult to secure thedurability of the cage 6.

An object of the roller bearing of this invention is to solve theproblems mentioned above.

DISCLOSURE OF THE INVENTION

The roller bearing of this invention comprises: an inner race having acylindrical inner-ring raceway around its outer peripheral surface, anouter race having a cylindrical outer-ring raceway around its innerperipheral surface, and a plurality of rollers located between theouter-ring raceway and inner-ring raceway that can rotate freely; andflange sections, wherein of both ends in the axial direction of theouter-ring raceway and inner-ring raceway, the flange sections areformed at least on the axially opposite ends with respect to the outerring raceway and inner ring raceway, respectively. Axial loads on theroller bearing are supported by the engagement between the side surfacesof the flange sections and the end surfaces in the axial direction ofthe rollers. Particularly, in the case of the roller bearing of thisinvention, the outer peripheral surfaces of the rollers are cylindricalin shape, and the sections of the opposite ends in the axial directionof the rollers near the outer diameter coming into contact with the sidesurfaces of the flanged sections are formed in a tapered convex surfacetilted in a direction such that the outer diameter is increased towardsthe axial center of the rollers. In addition, the portion of the sidesurface of the flanged section coming into contact with the taperedconvex surface is formed in a tapered convex surface or tapered concavesurface having a generatrix with the same tilting angle to thegeneratrix of the tapered convex surface. In addition, of the taperedconvex surfaces in the opposite ends of the rollers, the line connectingany point on the generatrix of the portion coming in contact with thetapered convex surface or tapered concave surface of the flanged sectionwith the center of the rollers coincides with the line normal to thegeneratrix at this point.

Incidentally, the point on the generatrix of the contact sections existin the middle portion of the ganeratrix at this portion. This middleportion is between the opposite ends of the generatrix of the portionand not limited to the central portion of the generatrix at thisportion. (Of course, the central portion is included, and the portionsadjacent to the both ends are included.) What is important is that theline normal to the middle portion at any point passes through the centerof the rollers. In other words, it is enough that the line vertical tothe generatrix at the contact sections can be drawn from this center.

The generatrix of the contact sections means an overlapping sectionbetween the generatrix of the tapered convex surface existing on theopposite ends of the rollers and the generatrix of the tapered convexsurface or tapered concave surface of the flanged sections coming intocontact with each other.

In the case of the roller bearing of this invention, the condition ofcontact between the end surfaces in the axial direction of the rollersand the side surfaces of the flange sections can be taken to be linearcontact, so that a condition near the rolling contact (condition wherethe rolling component is larger than the sliding component) is achieved.Therefore, even when rotating at high speed, it is difficult for damagesuch as slide marks, smearing, scraping, seizure and the like to occur,and even in the case of impact loads, vibrating loads, or repeatedloads, its seizure resistance can be maintained.

Moreover, at the area of contact between the tapered convex surfaces ofthe rollers and the tapered convex surfaces or tapered concave surfacesof the flange sections, the force due to axial loading and radialloading is applied in the direction normal to this area of contact. Inaddition, the forces applied in the direction normal to these areas ofcontact act toward the center of the rollers and cancel each other out.In other words, of the tapered convex surfaces on both ends of therollers, a line is provided for connecting any point on the genetatrixin contact sections that come into contact with the tapered convex orconcave surfaces of the flange sections with the center of the rollers,and this line coincides with the line normal to the generatrix at thatcontact section, so that the forces due to the axial load and radialload act toward the center of the rollers and cancel each other out.Therefore, it becomes difficult for a force to act that will cause therollers to displace.

For example, it is also possible to greatly reduce (almost to zero) thetilt moment applied to the rollers, and it becomes difficult for theaxis of rotation of the rollers to come out of alignment with the axisof rotation for the inner race and outer race, and thus it becomesdifficult for edge loading to occur on the side surfaces of the flangesections and on the inner-ring raceway and outer-ring raceway. As aresult, the bearing performance for axial load performance at the areaof contact can be improved (no damage such as scraping or seizure occursat the area of contact, while it becomes possible to support greateraxial loads), and since the roller bearing does not need to be used incombination with other rolling bearings, it also becomes possible tolower costs of the bearing by making it more compact and simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a half of a first example of theembodiment of the Invention.

FIG. 2 is an enlarged view of a roller.

FIG. 3 is an enlarged cross sectional view of part of an inner ring.

FIG. 4 is a plan view of part of a retainer.

FIG. 5 is a cross sectional view of part of a second example of theembodiment of the present invention.

FIG. 6 is a cross sectional view of part of a third example of theembodiment of the present invention.

FIG. 7 is a cross sectional view of part of a fourth example of theembodiment of the present invention.

FIG. 8 is cross sectional view of part of a fifth example of theembodiment of the present invention.

FIG. 9 is a cross sectional view of part of a sixth example of theembodiment of the present invention.

FIG. 10 is a cross sectional view of part of a seventh example of theembodiment of the present invention.

FIG. 11 is a cross sectional view of a half of an eighth example of theembodiment of the present invention.

FIG. 12 is a cross sectional view of a half of a ninth example of theembodiment of the present invention.

FIG. 13 is a cross sectional view of part of an example of theconventional structure of the roller bearing.

FIG. 14 is a plan view of part of a retainer.

DESCRIPTION OF THE BEST EMBODIMENT TO WORK THE INVENTION

FIGS. 1 to 4 show a first example of the embodiment of the invention.This example is characterized in that both of the end surfaces in theaxial direction of the rollers 5 a and the inner surface 11 a, 11 a ofthe outward and inward facing flange sections 8 a, 10 a are tailored inshape. The construction and function of all other parts aresubstantially the same as those of the roller bearing 1 that is shown inFIG. 13 and described above, and the same symbols are given to likeparts, and any redundant explanation is simplified and only the mainparts of this example will be explained here.

In the case of the roller bearing la of this example, the surfaces onthe axially opposite ends of the rollers 5 a have a section that fitswith the inner surfaces 11 a, 11 a that are formed on the outward-facingand inward-facing flange sections 8 a, 10 a of the inner race 2, outerrace 3 and flanged ring 4. These sections of the rollers 5 are shaped asshown in FIG. 2 such that they are tapered convex surfaces 22, 22inclined such that the outer diameter increases in the direction towardthe middle in the axial direction of the roller 5 a. This kind oftapered convex surface 22, 22 can be manufactured at lower cost thanwhen the surface of this section is a spherical convex surface. On theother hand, of the inner surfaces 11 a, 11 a of the outward-facingflange sections 8 a, 8 a, at least sections that come into contact withthe tapered convex surfaces 22, 22 of the rollers 5 a, are taperedconvex surfaces having a generatrix with the same angle of inclinationas the generatrix of the tapered convex surfaces 22, 22 as shown in FIG.3. FIG. 3 shows only the inner race 2, however, as shown in FIG. 1, ofthe inner side surfaces 11 a, 11 a of the inward-facing flange section10 a, 10 a of the outer race 3 and the flanged ring 4, at least contactsections that fit with the tapered convex surfaces 22, 22 of the rollers5 a, are tapered concave surfaces having a generatrix with an angle ofinclination that is the same as that of the generatrix of the taperedconvex surfaces 22, 22, in substantially the same way as for theoutward-facing flange sections 8 a, 8 a of the inner race 2.

Furthermore, in the case of this example, as shown in FIG. 2, of thetapered convex surfaces 22, 22 on both ends of the roller 5, contactsections come in contact with the tapered convex or concave surfaces ofthe outward-facing and inward-facing flange sections 8 a, 10 a, and theconnecting line ‘X’ that connects the centers S, S of the generatrix ofthe contact sections with the center O of the roller 5 coincides withthe line normal to the generatrix of this centers S, S. Also, togetherwith this, as shown in FIG. 1 and FIG. 3, of the tapered convex surfacesor tapered concave surfaces of the outward-facing and inward facingflange sections 8 a, 10 a, at the sections which come into contact withthe tapered convex surfaces 22, 22 on both ends of the roller 5 a, theconnecting line ‘X’ that connects the center O of the roller 5 a withthe center S, S of the generatrix of the corresponding side surfacesections also coincides with the line normal to the generatrix of at thecenters S, S. Therefore, the force applied to the areas of contactbetween the tapered convex sections 22, 22 of the roller 5 a and thetapered convex surface or tapered concave surface of the outward-facingand inward-facing flange sections 8 a, 10 a due to axial loads andradial loads is applied toward the center O of the roller 5 a as shownby arrow F in FIG. 2.

In the case of the roller bearing la of this example, the tapered convexsurfaces 22, 22 are formed on the end surfaces on the axially oppositesides of the rollers 5 a, and of the inner side surfaces 11 a, 11 a ofthe outward-facing and inward-facing flange sections 8 a, 10 a, contactsections come into contact with the end surfaces of the rollers 5 a suchthat the contact sections are tapered convex surfaces or tapered concavesurfaces having generatrix with the same angle of inclination as thegeneratrix of tapered convex surfaces 22, 22. Therefore, the conditionof contact between these surfaces can be taken to be linear contact, sothat a condition near the rolling contact (the rolling component islarger than the sliding component) is obtained. As a result, sliding atthe area of contact between these surfaces is reduced even at high rpm,and thus it is possible to reduce damage such as sliding marks,smearing, scraping, seizure and the like, and it is possible to maintainseizure resistance even when impact loads vibrating loads or repeatedloads are applied.

At the contact sections between the tapered convex surfaces 22, 22 ofthe rollers 5 a and the tapered convex surfaces or tapered concavesurfaces of the outward-facing and inward-facing flange sections 8 a, 10a, the forces due to axial loads and radial loads are applied in thedirection normal to the generatrix of each surface at these areas ofcontact. Also, the forces applied in the direction normal to these areasof contact act in the direction toward the center O of the roller 5 a,and cancel each other out, respectively. In other words, of the taperedconvex surfaces 22, 22 on both ends of the roller 5 a, since the line Xconnecting the center O of the roller 5 a with the centers S, S of thegeneratrix of the contact sections in contact with the tapered convexsurfaces or tapered concave surfaces of the outward-facing andinward-facing flange sections 8 a, 10 a, coincides with the line normalto the generatrix of these center points S, S, the forces F due to axialloading and radial loading (see FIG. 2) act in a direction toward thecenter of the roller 5, and cancel each other out.

Therefore, it becomes difficult for forces that would displace therollers 5 a to occur. For example, it is also possible to greatly reduce(to nearly 0) the tilt moment applied to the rollers 5 a as well, and itbecomes difficult for the axis of rotation of the rollers 5 a to comeout of alignment with the center axis of the inner race 2 and outer race3, and thus it also becomes difficult for edge loading to occur on theinner side surfaces 11 a, 11 a of the outward-facing and inward-facingflange sections 8 a, 10 a and on the inner-ring raceway 7 and outer-ringraceway 9. As a result, it is possible to improve the axial loadcapability at the areas of contact (capability to support large axialloads without damage such as scraping and seizure occurring at the areasof contact), and since it is not necessary to use the roller bearing incombination with other rolling bearings, it is possible to simplify andmake the rotation support section more compact, and thus further reducethe cost by making the roller bearing more compact and simple.

Since the shape of the outer periphery at the opposite ends in the axialdirection of the rollers 5 a is relatively smooth due to the existenceof the tapered convex surfaces 22, 22, the shape of the pockets 12 a, 12a in the cage 6 for holding the rollers 5 a can be made relativelysmooth at the comers as shown in FIG. 4. Therefore, when the rollingcontact surface of the rollers 5 a comes into contact with the insidesurface of the pockets 12 a, 12 a, the stress applied to the corners canbe kept low, and so the durability of the cage 6 can be secured.

Next, FIG. 5 shows a second example of the embodiment of the invention.In the case of this example, the cage 6 a, which holds the rollers 5 asuch that they rotate freely, is a so-called “rivet-fixed, machinedcage”. In other words, in the case of the first example shown in FIG. 1,the cage is a machined cage 6 that is a single member made out ofsynthetic resin or metal and formed in a generally cylindrical shapewith a plurality of pockets 12 formed at equal intervals around thecircumference in the axially middle section. On the other hand, the cage6 a assembled in this example is made out of synthetic resin or metaland formed generally into a comb-type ring shape, and comprises a mainmember 13, which has a plurality of pockets formed at equal intervalsaround the circumference such that each pocket has one end (right end)open on the one axial end surface (right end surface) of the main member13, and a circular ring member 14, which is also made out of syntheticresin or metal, that covers the open end of the pockets. Also, rivets 15are located in the column sections of the main member 13 between thepockets 12 such that they penetrate through the column sections and thecircular ring member 14 in the axial direction, and connect the mainmember 13 with the circular ring member 14, so that they cannot beseparated. The other construction and function of this embodiment,including the shape of the rollers 5 a and outward-facing flangesections 8 a and inward-facing flange sections 10 a, are substantiallythe same as those of the first example described above.

Next, FIG. 6 shows a third example of the embodiment of the presentinvention. While, in the first example shown in FIG. 1 and the secondexample shown in FIG. 5, the invention is applied to a NP-type rollerbearing 1 in which a flanged ring 4 is located on one end (left end) inthe axial direction of the outer race 3, in this example, the inventionis applied to a NUP-type roller bearing la in which a flanged ring 4 ais located on one end (left end) in the axial direction of the innerrace 2 a. In the case of this example as well, the sections on both endsurfaces in the axial direction of the rollers 5 a that fit with theinner side surfaces 11 a, 11 a of the outward-facing and inward-facingflange sections 8 a, 10 a have tapered convex surfaces 22, 22 that areinclined in the direction such that the inner diameter becomes larger inthe direction toward the middle in the axial direction of the roller 5a.

And, in addition, of the tapered convex surfaces 22, 22, the line X forconnecting the center points S of the generatrix of the contact sectionswith the tapered convex surface of the outward flange section 8 a, thecenter point S of the generatrix of the contact sections with thetapered concave section of the inward facing flange portion 10 a withthe center O of the roller 5 a coincides with the line normal to therespective generatrix.

On the other hand, the sections of the inner side surfaces 11 a, 11 a ofthe outward-facing and inward-facing flange sections 8 a, 10 a cominginto contact with the tapered convex surfaces 22, 22 of the rollers 5 aare tapered convex surfaces (in the case of the inner side surface 11 aof the outward-facing flange section 8 a) or tapered concave surfaces(in the case of the inner side surface 11 a of the inward-facing flangesection 10 a) whose generatrix has an angle of inclination that is thesame as those of the tapered convex surfaces 22, 22. Furthermore, in thecase of this example, the cage 6 b, which holds the rollers 5 a suchthat they can rotate freely, is a so-called “pressed cage” that is madeby pressing a metal plate. This cage 6 b is formed such that one end(left end) in the axial direction bends outward in the radial direction,and similarly, the other end (right end) bends inward in the radialdirection. The other construction and function are substantially thesame as that of the first example described above.

Next, FIG. 7 shows a fourth example of the invention. While in the caseof the first and second examples shown in FIGS. 1 and 5, the inventionis applied to a NP-type roller bearing la in which a flanged ring 4 islocated on one end in the axial direction (left end) of the outer race3, in the case of this example, the invention is applied to a NF-typeroller bearing la in which the flanged ring 4 is omitted, and the inwardfacing flange section 10 a is formed only on one (left end) of theopposite ends of the outer race 3 b. In this example, axial loads aresupported in only one direction. In other words, axial loads applied onone side surface (left side surface) of the outer race 3 b from one side(left side) to the other (right side) are supported, and axial loadsapplied on the other side surface (right side surface) of the inner race2 from the other side (right side) to the one side (left side) aresupported. In the case of supporting axial loads in only one directionin this way, there is no axial load applied between the inner sidesurface 11 a of one (left one) of the outward-facing flange sections 8a, 8 a formed on both ends of the inner race 2 and one end surface (leftend surface) in the axial direction of the roller 5 a. Therefore, theinner side surface 11 a of that one outward-facing flange section 8 adoes not necessarily need to be a tapered convex surface, however, inthe case of this example, in order to do away with any special assemblydirection of the inner race 2, both inner side surfaces 11 a, 11 a ofthe outward facing flange sections 8 a, 8 a are tapered convex surfaces.The other construction and function, including the shape of the rollers5 a, and outward-facing and inward-facing flange sections 8 a, 10 a aresubstantially the same as those of the first example described above.

Next, FIG. 8 shows a fifth example of the embodiment of the invention.While in the case of the fourth example shown in FIG. 7, the inventionis applied to a NF-type roller bearing la in which an inward-facingflange section 10 a was formed on only one end (left end) of the twoends of the outer race 3 b, in the case of this example, the inventionis applied to a NJ-type roller bearing la in which the outward-facingflange section 8 a is formed on only one end (left end) of the two endsin the axial direction of the inner race 2. In the case of this exampleas well, axial forces only in one direction are supported as explainedin FIG. 7, and the sections on both ends in the axial direction of therollers 5 a that come into contact with the inner side surfaces 11 a, 11a of the outward-facing and inward-facing flange sections 8 a, 10 a aretapered convex surfaces 22, 22 that are inclined in a direction suchthat the outer radius becomes larger in the direction toward the middlein the axial direction of the roller 5 a. Also, together with this, ofthe tapered convex surfaces 22, 22 on both ends of the roller 5 a, theline ‘X’ connecting with the center O of the roller 5 a with the centersS, S of the generatrix of the contact sections that come in contact withthe tapered convex or tapered concave surfaces of the outward-facing andinward-facing flange sections 8 a, 10 a coincides with the line normalto the generatrix of the centers S, S.

On the other hand, the contact sections of the inner side surfaces 11 a,11 a of the outward-facing and inward-facing flange sections 8 a, 10 athat fit with tapered convex surfaces 22, 22 of the rollers 5 a aretapered convex surfaces or tapered concave surfaces having a generatrixwith the same angle of inclination as the generatrix of the taperedconvex surfaces 22, 22. Furthermore, in the case of this example, thecage 6 c, which holds the rollers 5 a such that they can rotate freely,is a so-called “pin-type cage” that comprises a pair of elements 16, 16formed in a ring shape and which are connected by a connecting pin 17that passes through the center axis of the rollers 5 a such that theycannot be separated. The other construction and function aresubstantially the same as those of the fourth example described above.

Next, FIG. 9 shows a sixth example of the embodiment of the invention.While in the case of examples 1 to 5 shown in FIGS. 1 to 8, theinvention is applied to a roller bearing la having the cage 6, 6 a, 6 b,6 c, in the case of this example, the invention is applied to a fullcomplement roller bearing (full complement rolling bearing) 1 b that hasno cage. In the case of this example, it is possible to increase thenumber of rollers 5 a in the place of the cage that is not used.Therefore, it is possible to support more load without having toincrease the size of the roller bearing 1 b. Of course, in this exampleas well, the sections of the surfaces on both ends in the axialdirection of the rollers 5 a that fit with the inner side surfaces 11 a,11 a of the outward-facing and inward-facing flange sections 8 a, 10 aare tapered convex surfaces 22, 22 that are inclined in a direction suchthat the outer radius becomes larger in the direction toward the middlein the axial direction of the roller 5 a. Also, together with this, theline X′ connecting the centers S, S of the generatrix of the sections ofthe tapered convex surfaces 22, 22 on both ends of the roller 5 a thatcomes in contact with the tapered convex or tapered concave surfaces ofthe outward-facing and inward-facing flange sections 8 a, 10 a with thecenter O of the roller 5 a coincides with the line normal to thegeneratrix of the center S, S. On the other hand, the sections of theinner side surfaces 11 a, 11 a of the outward-facing and inward-facingflange sections 8 a, 10 a that fit with tapered convex surfaces 22, 22of the rollers 5 a are tapered convex surfaces or tapered concavesurfaces having a generatrix with the same angle of inclination as thegeneratrix of the tapered convex surfaces 22, 22. The other constructionand function are the same as those of the first example.

Next, FIG. 10 shows a seventh example of the embodiment of theinvention. Similar to the sixth example shown in FIG. 9, the inventionin this example is applied to a full complement roller bearing 1 b thathas no cage. Also, in the case of this example, similar to the fourthexample shown in FIG. 7, the roller bearing 1 b is a NF-type fullcomplement roller bearing in which an inward-facing flange section 10 ais only located on one end (left end) of the outer race 3 b with theflanged ring 4 omitted. The other function and construction, includingthe shape of the roller 5 and outward-facing and inward-facing flangesections 8 a, 10 a are substantially the same as those of the fourth andsixth examples described above.

Next, FIG. 11 shows an eighth example of the embodiment of theinvention. While in the case of the first to seventh examples shown inFIGS. 1 to 10, the invention is applied to a single-row roller bearing 1a, 1 b, in the case of this example, the invention is applied to amultiple-row roller bearing 18. In other words, multiple rows ofcylindrical shaped outer-ring raceways 9, 9 are formed around the innerperipheral surface of the cylindrical shaped outer race 19. Also, aninward-facing flange section 10 b is formed all the way around thecircumference in the middle of the inner peripheral surface of thisouter race 19 in the section between both outer-ring raceways 9, 9.Moreover, flanged rings 4, 4 are located on both end surfaces in theaxial direction of this outer race 19, and these flanged rings 4, 4 havea section that protrudes further inward in the radial direction than theouter-ring raceway 9, 9 to form the inward-facing flange sections 10 a,10 a. Also, a pair of inner races 2, 2 are located on the inner diameterside of the outer race 19 such that their inside end surfaces in theaxial direction come together. Cylindrical shaped inner-ring raceways 7,7 are formed around the outer peripheral surface of these inner races 2,2. Moreover, outward-facing flange sections 8 a, 8 a are formed all theway around the circumference on the ends in the axially opposite sidesof each of the inner-ring raceways 7, 7. A plurality of rollers 5 a, 5 aare located between each of the outer-ring raceways 9, 9 and inner-ringraceways 7, 7, and held in cages 6, 6 such that they can rotate freely.In this condition, the end surfaces on the axially opposite ends of therollers 5 a, 5 a face toward the side surfaces 11 a, 11 a of theoutward-facing and inward-facing flange sections 8 a, 10 a, 10 b.

Particularly, in the case of this example, the end surfaces on theaxially opposite sides of the rollers 5 a have contact sections that fitwith the inner side surfaces 11 a, 11 a of the outward-facing and theinward-facing flange sections 8 a, 10 a, 10 b of the inner races 2, 2,outer race 19 and flanged rings 4, 4, and the contact sections havetapered convex surfaces 22, 22 that are inclined such that the outerdiameter increases in the direction toward the middle in the axialdirection of the roller 5 a. In addition, the line ‘X’ connecting withthe center O of the roller 5 with the centers S, S of the generatrix ofthe contact section of the tapered convex surfaces 22, 22 on both endsof the roller 5 a that comes in contact with the tapered convex ortapered concave surfaces of the outward-facing and inward-facing flangesections 8 a, 10 a, 10 b coincides with the line normal to thegeneratrix of the centers S, S. On the other hand, the sections of theinner side surfaces 11 a of the outward-facing and inward-facing flangesections 8 a, 10 a, 10 b that fit with tapered convex surfaces 22, 22 ofthe rollers 5 a are tapered convex surfaces or tapered concave surfaceshaving a generatrix with the same angle of inclination as the generatrixof the tapered convex surfaces 22, 22.

In the case of this example as well, the condition of contact betweenthe end surfaces on the axially opposite ends of the rollers 5 a and thecorresponding side surfaces 11 a, 11 a of the outward-facing andinward-facing flange sections 8 a, 10 a, 10 b can be taken to be linearcontact and near to a condition of rolling contact. Therefore, even whenrotating at high speed, it is possible to reduce damage such as slidemarks, smearing, scraping and seizure, and even when impact loads,vibrating loads or repeated loads are applied, it is possible to easilymaintain seizure resistance.

Also, the forces that are applied to the contact sections between thetapered convex surfaces 22, 22 of the rollers 5 a and the tapered convexor tapered concave surfaces of the outward-facing and inward-facingflange sections 8 a, 10 a, 10 b due to axial loads and radial loads actin the direction toward the center of the rollers 5 a and cancel eachother out. Therefore, it becomes difficult for forces to act that causethe rollers 5 a to displace. As a result, it is possible to improve theaxial load capability at the areas of contact (capability to supportlarger axial loads without damage such as scraping or seizure occurringat the areas of contact), and since the roller bearing does not need tobe used in combination with other rolling bearings, it is possible tosimplify and make the rotation support section more compact, and thus itis also possible to reduce cost by simplifying and making the rollerbearing more compact.

Next, FIG. 12 shows a ninth example of the embodiment of the invention.In the case of this example, the invention is applied to a multi-row(four row) roller bearing 18 a. In other words, a plurality of rows ofcylindrical shaped outer-ring raceways 9, 9 are formed around the innerperipheral surface of a pair of concentric cylindrical shaped outerraces 19, 19. Inward-facing flange sections 10 b, 10 b are formed allthe way around the circumference in the sections between both outer raceraceways 9, 9 in the middle in the axial direction of the innerperipheral surface of these outer races 19, 19. Moreover, flanged rings4, 21 are located in the sections between the axially outer ends and theaxially inner ends of the outer races 19, 19, and the parts of theseflanged rings 4, 21 that protrude further inward in the radial directionthan the outer-ring raceways 9, 9 act as the inward-facing flangesections 10 a, 10 b. Also, a pair of inner races 20, 20 are located onthe inner-diameter side of the outer races 19, 19 such that they areconcentric and that the axially inner ends come together. A plurality ofcylindrical shaped inner-ring raceways 7, 7 is formed around the outerperipheral surfaces of these inner races 20, 20. Outward-facing flangesections 8 b, 8 a are formed all the way around the circumference in thesection between both inner-ring raceways 7, 7 in the middle in the axialdirection of the outer peripheral surface of the inner races 20, 20, andon the axially opposite ends of the inner-ring raceways 7, 7. Inaddition, a plurality of rollers 5 a, 5 a are located between each ofthe outer-ring raceways 9, 9 and inner-ring raceways 7, 7, and rotatablyheld by cages 6, 6. In this condition, the end surfaces in the axialdirection of the rollers 5 a, 5 a, face toward the side surfaces 11 a,11 a of the outward-facing and inward-facing flange sections 8 a, 8 b,10 a, 10 b.

In the case of this example, the axially opposite end surfaces of therollers 5 a have contact sections that fit with the side surfaces 11 a,11 a of the outward-facing and inward-facing flange sections 8 a, 8 b,10 a, 10 b, which are formed around the inner races 20, 20, outer race19, 19 and flange rings 4, 21, and the contact sections have taperedconvex surfaces 22, 22 that are inclined such that the outer diameterincreases in the direction toward the middle in the axial direction ofthe roller 5 a. In addition, the line ‘X’ connecting the center o of theroller 5 a with the centers S, S of the generatrix of the sections ofthe tapered convex surfaces 22, 22 on both ends of the roller 5 a thatcomes in contact with the tapered convex or tapered concave surfaces ofthe outward-facing and inward-facing flange sections 8 a, 8 b, 10 a, 10b coincides with the line normal to the generatrix of the centers S, S.On the other hand, the contact sections of the side surfaces 11 a, 11 aof the outward-facing and inward-facing flange sections 8 a, 8 b, 10 a,10 b that fit with tapered convex surfaces 22, 22 of the rollers 5 havetapered convex surfaces or tapered concave surfaces having a generatrixwith the same angle of inclination as the generatrix of the taperedconvex surfaces 22, 22. The other construction and function aresubstantially the same as those of the eighth example described above.

Applicability to the Industry

The roller bearing of this invention is constructed and functions asdescribed above, so the contact state of the contact sections where theside surface of the flanged portion comes into contact with the axialend surface of the rollers can be placed substantially in the rollingcontact state, thereby improving anti-seizure property at the contactsections. With the improvement of anti-seizure property based onreduction in tilt-moment, the axial load capacity can be sufficientlyimproved at the contact sections. In addition, in the case where a cageis used, the durability (anti-damage strength) of the cage can beimproved. As a result, this roller bearing can be widely used in allkinds of rotation support that are operated under severe conditions,making it possible to make the rotation support more compact while atthe same time maintain durability of the rotation support.

1. A roller bearing comprising: an inner race having an outer peripheralsurface formed with a cylindrical inner-ring raceway therearound, anouter race having an inner peripheral surface formed with a cylindricalouter-ring raceway therearound, and a plurality of rollers rotatablylocated between the outer-ring raceway and the inner-ring raceway, and aflange section formed on at least opposite ends in the axial directionof the ends in the axial direction of the outer-ring raceway andinner-ring raceway, such that axial loads are supported by theengagement between the side surfaces of the flange sections and the endsurfaces in the axial direction of the rollers, the outer peripheralsurface of the rollers being formed in a cylindrical surface, such thatthe section near the outer diameter of the axial opposite end surfacescoming into contact with the side surface of the flange section isformed in a tapered convex shape that is inclined such that the outerdiameter becomes larger toward the middle in the axial direction of theroller, the side surface of the flange sections mating with the taperedconvex shape, being formed in a tapered convex shape or tapered concaveshape having a generatrix that is at the same angle of inclination asthe generatrix of the tapered convex surface, wherein a generatrixdefines the contact section at which the tapered convex surface of theends of the rollers comes into contact with the side surface in thetapered convex or concave shape of the flange sections, and wherein anypoint on the generatrix is connected by a line with the center of therollers, and wherein this line coincides with the line normal to thegeneratrix at the point.